OK, so what the skinny on holdfast

[David Nelson1]

From what I have read it seems that a 3/4 hole is required and different store bought holdfast work better with different thickness tops. I bought a pair made by Peter Ross (thanks Kelly) pretty standard 3/4 shaft 12 " long with a 6 inch reach. My top with be 4" +/- 1/16th. Will a 3/4 hole work or will I need to dedicate some other size hole for just the hold fast?

Sorry if this is a repeat question and has been hashed out before.

[Jim Matthews]

All my holdfasts measure 3/4, so do the bench top holes.

If I find one of the holes impassible, I ream it with a round file some.
I don't want the hold fasts to come out too easy.

[Gary Hodgin]

+1, same here. The issue I had was with the depth of my bench. My bench top is a Sjoberg with 3" aprons and either 1.5" or 1.75" (can't) remember. My first set of holdfasts wouldn't work well in my shallower holes. The Gramarcy's work well in both sizes. I don't think you'll have a problem with the 4" holes at all. The three-quarter inch holes are correct.

[Ryan Baker]

You will probably be fine with the 3/4" holes, and will want that size for other things. Try it first and see how it goes.

If you ave problems, start by roughing up the shanks of the holdfasts a bit with some sandpaper -- horizontally around the shaft, not lengthwise. Another option is to counterbore a larger hole from the bottom side -- effectively reducing the thickness of the top around the holes. Or you could open up the holes a little -- which is can help with really thick tops.

[Dave Cav]

I just got a pair of Gramarcys. My bench top is about 3 1/2" thick and my dog holes are 3/4" square. The holdfasts work fine, but they need to be aligned across the corners of the dog holes.

[David Nelson1]

I just got a pair of Gramarcys. My bench top is about 3 1/2" thick and my dog holes are 3/4" square. The holdfasts work fine, but they need to be aligned across the corners of the dog holes.

Can you explain?

[Dave Cav]

Can you explain?

The "arm" of the holdfast, the part that actually holds the work down, needs to be at (about) 45 degrees to the straight sides of the dog hole. Apparently my dog holes are a tiny bit too small in the square direction for the shaft to grab, but in the diagonal direction there's enough room. I'm going to try the sandpaper trick next time I think about it.

[David Nelson1]

Having to reread that a few times I finally got it LOL